G4 stuck on boot logo, NO FASTBOOT

[Xenosender]

Hi all
I wanted to root/install custom recovery on my brand new H815.
I :
- unlocked the bootloader
- installed (flashed) TWRP through ADB and fastboot. Seemed to work (install ok-ed), but impossible to lauch TWRP though recovery : with adb reboot recovery, I had a small icon of the dead android minion, and with the buttons, I stayed on stock recovery (which only offers to wipe all user data)

So i booted on TWRP (using fastboot boot twrp.img), which worked, but from there instead of installing TWRP first, I flashed the super SU img to root the phone.

Problem is : since then, I am stuck on the starting LG logo :
- I can access the stock recovery, already wiped data, but to no avail
- I cannot launch fastboot, even utilizing vol up + start buttons
- therefore I don't have the download mode
- phone is not recognized by my computer (aka nothing happens), so I can't access it through console adb and fastboot

Could anyone help me on how to unbrick my phone ?
I have seen pages about a shorting test point technique to get into QHSUSB bulk mode, but without clear explanations on how to perform it...

 

[LeoRex]

Quick question.. what version was the G4 at prior to all this? 5.1 or 6.0? That makes a huge difference.

 

[Xenosender]

oh yes, sorry about that.
It was 6.0 from the start.

 

[LeoRex]

What version of twrp did you install? I assume it was twrp-3.0.0-0-h815.img

Second question... Did you have the OEM unlock flag check in Developer Options... and was it encrypted out of the box?

 

[LeoRex]

Oh.... try booting into the TWRP image (via the img file) Can you get into fastboot (boot into the booloader) that way?

 

[Xenosender]

So :
- I tried this one first, but it did not work (because of LG overriding the recovery everytime, as I found out later). Last one I installed was the twrp-2.8.6.0-hima.img
- I did check the OEM unlock flag
- No Idea, but I don't think so

how can I boot on the twrp image if i can't get adb or fastboot to see my device as it did before ?

On a better note, I was in fact able to enter download mode (so no fastboot, crappy stock recovery, but download mode accessible)
This lead me to the "Firmware update" screen, so maybe that's a good start

 

[LeoRex]

Yeah, I'd roll it back... go hunt down the instructions to load the 10N (I think that's what it is) factory 6.0 image and then start all over... Over on XDA, you should find every file you need.

twrp-2.8.6.0-hima.img? Is 'hima' the internal name for the G4? never heard that before.

 

[Xenosender]

Yeah, that's how I finally got out of it.

So : if you're stuck on start screen, no fastboot BUT download mode accessible, use :
forum.xda-developers.com/ g4/ general/ guide-lg-g4-stock-firmware-to-stock-kdz-t3107848
Not the main post, but the first answer, which uses a software called LGUp to flash images.

I used that to go back to stock android.

Thanks for taking some time to answer !

 

[LeoRex]

I wonder if you had a bad TWRP flash before. I did the same operation with my D811... Worked without a hitch

 

[Xenosender]

In fact the problem didn't come from TWRP but from the root.
I made the mistake of trying to root with superSU without installing TWRP (i just booted on it). Turns out superSU did not work for me (no boot later on, no access to fastboot), and I had not TRWP installed locally, so i was stuck.

After unbricking my phone by reinstalling stock, I :
- booted on TRWP, copied it on my phone and flashed it so that it was finally installed
- rooted using the autoroot kernel, which did the trick

It's been a while since I had so much trouble rooting a phone, though...

 

[kraze4u]

Should have just bought the Nexus 6P.

 

[LeoRex]

It's been a while since I had so much trouble rooting a phone, though...

Well, once they converted the G4 to use fastboot, that should have been easier... As easy as a Nexus.

 

[Definitely Oldfag]

I did the exact same thing you did and am now stuck in in the bootloop. How exactly did you manage to get into download mode? The button combination with the cable doesn't work for me. Rest in peaces 320 euro's on my brand new phone if you can't help me either :'(

EDIT*: I thought you also had to hold the power button to get into download mode, but you only need to hold the volume up button and than plug in the cable.

 

[Xenosender]

yep, button up and plug in the cable do the trick
Hope you solved the problem